Supporting-pin for line-insulators.



No. 758,179. PATENTED APR. 26, 1904.

- J. D. HILLIABD, JR. SUPPORTING PIN FOR LINE INSULATORS.

APPLIUATIC'N FILED JUNE 16, 1903- N0 MODEL.

l illll! uunnm ll /6 I i7/////%I\\\\\\ 776'f2755e5 F //7 v e/vfor UNITED STATES Patented April 26, 1904.

PATENT OFFICE.

SUPPORTING-PIN F OR LINE-INSULATORS- SPECIFICATION forming part of Letters Patent No.758,179, datedApril 26, 1904.

Application filed June 16, 1903. Serial No- 161,681. (No model.)

- tion.

This invention relates to supporting-pins for line-insulators; and its object is to strengthen the construction of overhead high-tension transmission-lines.

Experimental tests have proven that a pin for an insulator if made with a central steel rod and a porcelain outer shell will stand considerably more voltage before breaking down than either an all-iron or all-wood pin. My experiments have proven, however, that for heavy lines the porcelain outer shell or base is not satisfactory, because it is mechanically weak, due to a fault in construction, and it is to remedy this defect that I have devised the present invention. The ordinary pin comprises a steel bolt having a wooden screwthreacled bushing on its upper end to receive the porcelain insulator. Below the bushing is a bell-shaped porcelain sleeve surrounding the bolt and forming a base between the bushing and the cross-arm or other support. As

soon as a stress is applied to the insulator at-.

tached to the pin the wood sleeve and bolt are pulled over until the bolt comes in contactwith the porcelain sleeve. A tensile stress is thus applied tothe sleeve and causes it to break. greatly increase the break-down pressure, is

as follows: On top of the sleeve I place a flanged metal cap, which surrounds the upper end of the sleeve, or make this cap in one piece with the pin, the hole in the cap making a close fit on the bolt, and ample clearance between the sleeve and the bolt is provided.-

My plan, which tests have shown to bolt bears against the side of the hole, we have a large area under compression. The result is a great increase in the break-down strength of the piece. It is immaterial whether the cap is made separate from the pin or a part of it. The result is the same in both cases;

In the accompanying drawings, Figure 1 is a vertical section of a bolt, sleeve, cap, and washer supported on a cross arm. Fig. 2 shows the cap partly in section. Fig. 3 is an elevation of a bolt, partly in section, showing a,modification. Fig. 4 shows another modification.

The steel bolt 1 has near its upper end a I shoulder, preferably formed by an enlarged head 2, having external screw-threads 3 to receive the porcelain insulator. (Not shown.) I may use, however, the ordinary straightheaded bolt and wooden or metal bushing, as indicated in Fig. 4, in which case the shoulder is formed by the lower end of the bushing. The bolt is fastened in a cross-arm L or other suitable support, and between said support and the shoulder is a bell-shaped sleeve or base5, of porcelain-or other insulation. Between the shoulder and the top of the sleeve 5 I place an annular plate 6, of stiif sheet metal, such as steel, having a downwardly-extending outer flange 7, fitting the outside of the sleeve. The inner edge of the plate fits the shank of the bolt and is preferably provided with an inner flange 8. Between this cap and the sleeve is preferably placed a washer 9, of fiber or the like.

In the'modification shown in Fig. 8 the cap is integral with the bolt, being an invertedcup-shaped flange 10 on the lower end of the head 2. In either case the function of the cap is to transmit the side thrust of the bolt to the outer surface of the sleeve, and thus dis tribute it to such an extent as to avoid breaking the sleeve.

Having thus described'my invention, what I claim is 1. The combination with an insulatingsleeve, of a metal bolt adapted to receive an insulator, said bolt passing through said sleeve and leaving an annular space between it and said sleeve, and a metalcap rigidly carried by said bolt and having a flange fitting over the outside of said sleeve totransmit the side thrust of the bolt to the outer surface of the sleeve.

2. In an insulator, the combination with a metal bolt, adapted to receive an insulator and having a shoulder, of a sleeve of insulating material below said shoulder but not in contact with said bolt, an annular plate of metal fitting the bolt and lying between the shoulder and the top of the sleeve and provided with a downwardly-extending flange fitting the outside of said sleeve, and a washer of fiber or the like between said plate and sleeve.

' 3. The combination with an insulator-bolt,

a support therefor and an insulating bellshaped base surrounding but not in contact with said bolt and resting on said support, of

a sheet-metal platebetween said bolt and base, 

